In spermatozoa of many animals, the acrosome is an organelle that develops over the anterior half of the spermatozoon's head. It is a cap-like structure derived from the Golgi apparatus. Acrosome formation is completed during testicular maturation. In Eutherian mammals the acrosome contains digestive enzymes (including hyaluronidase and acrosin). A sperm cell, spermatozoon ( spermatozoa) (in Greek: sperma = semen and zoon = alive), or spermatozoan, is the haploid cell that is the male gamete. ... Schematic of typical animal cell, showing subcellular components. ... In cell biology, the Golgi apparatus (also called a Golgi body, Golgi complex, or dictyosome) is an organelle found in most eukaryotic cells, including those of plants, animals, and fungi. ... Eutheria is a taxon (specifically, an infraclass) nearly synonymous with Placentalia, containing the placental mammals and the nearest ancestors of placental mammals (which are known only from the fossil record). ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Ribbon diagram of the catalytically perfect enzyme TIM. Factor D enzyme crystal prevents the immune system from inappropriately running out of control. ... Hyaluronidase The hyaluronidases (EC 3. ... Acrosin (EC 3. ...

Acrosome reaction

layer that surrounds the egg. In some lower animal species a protuberance (the acrosomal process) forms at the apex of the sperm head, supported by a core of actin microfilaments. The membrane at the tip of the acrosomal process fuses with the egg plasma membrane. In some lower species, including sea stars and sea urchins, a major portion of the exposed acrosomal contents is a protein that temporarily holds the sperm on the egg surface. In mammals the acrosome reaction releases hyaluronidase and acrosin; their role in fertilization is not yet clear. It also alters a patch of pre-existing sperm plasma membrane so that it can fuse with the egg plasma membrane. Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... Hyaluronidase The hyaluronidases (EC 3. ... Acrosin (EC 3. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ...

See also

• Capacitation